Embodiments of the disclosed technology relates to an amorphous oxide thin film transistor, a method for manufacturing an amorphous oxide thin film transistor, and a display panel.
At present, amorphous silicon thin film transistors (TFT) and polysilicon TFTs are widely used in liquid crystal displays. Hydrogenated amorphous silicon (a-Si:H) TFTs have become mainly used for active matrix flat displays due to advantage of simply preparation process, excellent uniformity, or the like. However, a-Si:H TFTs have defects, such as low mobility, poor stability, or the like, and therefore are difficult to be used in the field of large-area AMOLED (Active Matrix Organic Light Emitting Diode). Compared with the amorphous silicon TFTs, the polysilicon TFTs have high mobility and good stability. Methods for preparing a channel portion of a polysilicon TFT mainly include solid phase crystallization (SPC) and excimer laser annealing (ELA). The former relates to a long time high temperature annealing process, so it can not be adopted for a large-area glass substrate; the later has some defects, such as poor uniformity, or the like, so it cannot be adopted for the large-area glass substrate also.
For realizing large-area AMOLED displaying, amorphous oxide TFTs mainly based on zinc oxide (ZnO) or tin oxide (SnO2) are used and combines the advantages of amorphous silicon and polysilicon TFTs, such as high carrier mobility, excellent uniformity, or the like, so this technology has attracted an increasing attention. However, the semiconductor channel made of amorphous oxide usually has high carrier concentration so that the threshold voltage becomes very low, even down to a negative value, that is, even if no gate bias voltage is applied, the device can not be turned-off completely. If the amorphous oxide is used to form the semiconductor channel with low carrier concentration and high resistance, a parasitic resistance of source and drain electrodes may be increased, and thus the current driving capacity is reduced.